1. Field of the Invention
This invention relates to a process for preparing codeinone from thebaine at a virtually quantitative yield.
2. Description of the Prior Art
The transformation of thebaine to codeinone can be carried out by a variety of different procedures.
Knorr and Horlein, Ber. 39, 1409 (1906), on the one hand, and Schopf and Hirsch, Anna. Chem. 489, 224 (1931), on the other hand, performed the hydrolysis of thebaine in an aqueous acid medium obtaining codeinone and methanol, but with very low yields.
The conversion of thebaine to codeinone via 14-bromocodeinone and neopinone was also attempted by Conroy and Krausz, J. Am. Chem. Soc., 77, 5960 (1955) and Bull, Soc. Chim. France 2148 (1960), but the number of steps required and the yield in each step make this method of little practical value.
This transformation was carried out with some success by several authors such as Gavard et al., Bull, Soc. Chim. France 1486 (1965), and has been the subject of different patents.
The yields obtained are found to be between 50% and 75%.